Hello,
Is there an recommended / easy way to filter out the elements shown in the default list dialog?
I have a List-relation in my ecore model but I do not want to see all elements from the model in the dialog when assigning the elements of that list.
(As an example you might think of showing only the classes with the same package
compared to shwoing all classes of the complete model as alternatives in the dialog).

Easy would me, some lines of code in adapting the editor, an extension point,..

So the idea is just to specialize the item property descriptor's getChoiceOfValues method to return only the choices you want. You might call supergetChoiceOfValues and filter it down to what you want, or, as in this case, gather the choices in some other way.

Ed, thank you very much this fast and perfect answer!
That was exactly what I was looking for.
So I added your proposed method (modified for my model) into the generated ItemProviders.
Also using super.getChoiceOfValues (object) was helpful.